Packaging machines are known that integrate the various components necessary to fill and seal a container into a single machine unit. This packaging process, generally stated, includes feeding carton blanks into the machine, sealing the bottom of the cartons, filling the cartons with the desired contents, sealing the tops of the cartons, and then off loading the filled cartons for shipping. The motion and I/O control of the packaging machine may be undertaken by an electronic control system.
Traditionally, control systems for packaging machines have utilized programmable logic controllers (PLC) to effect both motion and I/O control. PLC system architecture, however, is principally directed to I/O control and has only limited value as an axis controller. Such a system is described in U.S. Pat. No. 5,177,930, issued Jan. 12, 1993. As illustrated in the '930 Patent, a single PLC is utilized to control both the motion and the I/O.
Trends within the field of packaging machines point toward increasingly high capacity machines intended for rapid, continuous filling and sealing of a very large number of identical or similar packaging containers, e.g., containers of the type intended for liquid contents such as milk, juice, and the like. One such machine is disclosed in U.S. Ser. No. 08/190,546, filed Feb. 2, 1994, which is hereby incorporated by reference. The machine disclosed in the '546 application includes a plurality of processing stations, each station implementing one or more processes to form, fill, and seal the containers. Each of the processing stations is driven by one or more servomotors that drive the various components of each of the processing stations.
The increased throughput and decreased size requirements have increased the demands that are placed on the control systems that are employed. As the number of axes increases, the demands on the speed of the control system response also increases. The traditional single PLC control system is often inadequate to meet these speed requirements. Accordingly, a more sophisticated control system for a packaging machine of the foregoing type is desirable.